CN111630400A

CN111630400A - Method and device for monitoring power electronic components

Info

Publication number: CN111630400A
Application number: CN201980008087.8A
Authority: CN
Inventors: T·奥利克; M·霍曼; J·克勒科; H·拉巴
Original assignee: Automotive Traffic Engineering Co ltd
Current assignee: Automotive Traffic Engineering Co ltd; IAV GmbH Ingenieurgesellschaft Auto und Verkehr
Priority date: 2018-01-11
Filing date: 2019-01-10
Publication date: 2020-09-04
Also published as: US11209495B2; WO2019137581A1; US20210080510A1; DE102018100518A1

Abstract

The purpose of the present invention is to configure monitoring of power electronic components more efficiently and with more versatile use. This object is achieved according to the invention in that an electrical variable, which is initially an electrical input variable, is converted and/or changed by means of a power electronic component into at least one electrical output variable in a subsequent process by means of a conversion and/or change process/procedure which is carried out in conjunction with the power electronic component, wherein, during the conversion and/or change process, a bit stream is generated by means of a Delta Sigma modulator according to the invention, which bit stream represents the electrical variable, i.e. the electrical input variable or the at least one electrical output variable. According to the invention, a bit stream can also be generated by means of a plurality of Delta Sigma modulators, each bit stream representing a respective electrical variable, namely an electrical input variable and the at least one electrical output variable. According to the invention, the power electronic components are monitored by means of the bit stream generated in this way/by means of the bit streams generated in this way, the bit streams then being ready. It is important according to the invention that said bit stream/said bit streams are not demodulated so that there is very convincing information of the corresponding valid signal.

Description

Method and device for monitoring power electronic components

Technical Field

The invention relates to a method and a device for monitoring power electronic components having the features according to the claims.

Background

Monitoring of the state of power electronic components, such as inverters, according to document WO2001031770a1 is prior art. Said document describes a specific test sequence in which, in a test operation deviating from the normal operation of the inverter, a plurality of switched electronic components or switches of the power electronics assembly are switched on, while the other switches are switched off or open.

The tests are carried out before the inverter is operated, for example as described in document WO1994011747a 1.

According to the prior art, it is disadvantageous that the monitoring of the power electronics module with the switched-mode electronic component (here, respectively, the inverter) is not carried out during the actual operation of the inverter, i.e., during the conversion of the fed current type (direct current) into the respective other current type (alternating current). Therefore, the monitoring of the inverter is not carried out in real time and early identification of the fault is not ensured.

Disclosure of Invention

The purpose of the present invention is to configure monitoring of power electronic components more efficiently and with more versatility.

This object is achieved according to the invention in that the electrical variable is converted and/or changed by means of the power electronics module. In other words, the electrical variable is first an electrical input variable, which is converted in a subsequent process into at least one electrical output variable by a conversion and/or a process/process change in conjunction with the power electronics module. During the conversion and/or change, a bit stream is generated according to the invention by means of a Delta-Sigma (Delta-Sigma) modulator, which bit stream represents the electrical variable, i.e. the electrical input variable or the at least one electrical output variable. It is of course also possible according to the invention to generate a bit stream by means of a plurality of Delta Sigma modulators, which bit stream represents the respective electrical variable, i.e. the electrical input variable and the at least one electrical output variable. According to the invention, the power electronic components are monitored by means of the bit stream generated in this way/by means of the bit streams generated in this way (the bit streams are then ready). It is important according to the invention that said bit stream/said bit streams are not demodulated so that there is very convincing information of the corresponding valid signal.

Therefore, the power electronic component can be monitored in real time according to the invention. According to the invention, the behavior of the power electronics module, including the switch-mode element, can be analyzed or monitored in real time (i.e., during operation of the power electronics module, i.e., during the switching and/or changing process). On the one hand, during the switching/changing of the electrical input variable to the at least one electrical output variable by means of the power electronic component, a monitoring of the state of the component can be carried out by means of the data obtained in the manner according to the invention or by means of the bit stream/bit streams. On the other hand, however, faults can also be identified early during the switching/changing of the electrical input variable into the at least one electrical output variable on the basis of the data obtained in the manner according to the invention or on the basis of the bit stream/bit streams.

Furthermore, it is provided according to the invention that, during the changeover/change of the electrical input variable, a pattern recognition is carried out by means of the data obtained in the manner according to the invention or on the basis of the bit stream/bit streams.

Here, the result of the pattern recognition may be a load index relating to the power electronic component. Based on the load indicator, a service life indicator relating to the power electronic component can be formed, which service life indicator decreases over the operating time of the power electronic component. The service life indicator can also be formed according to the invention on the basis of a plurality of load indicators. The other load indicator is, for example, the power loss of the half bridge of the inverter and is formed according to the invention by means of the bit stream/bit streams, which are each provided by means of a Delta Sigma modulator. Yet another load index may be the power loss of a capacitor provided in the intermediate circuit of the inverter. According to the invention, the influence of the individual load indicators on the service life indicators can be weighted, i.e. one load indicator can act more strongly on the service life indicator than another load indicator.

According to the invention, a device for carrying out the method is also proposed, which comprises the power electronics to be monitored and at least one Delta Sigma modulator.

Further advantageous embodiments of the invention emerge from the following exemplary embodiments and the dependent claims. Here, the application of Delta Sigma pulse width modulation is exemplarily illustrated. However, the solution according to the invention can also be applied in combination with conventional pulse width modulation.

Detailed Description

The power electronics module 1 is in particular a power electronic control element comprising a switching element, wherein an electrical input variable is converted into at least one electrical output variable by means of the power electronics module 1, so that, for example, a direct voltage is converted into a single-phase or multi-phase alternating voltage. That is to say, the electrical input variable is influenced such that at least one electrical output variable which is different from the electrical input variable or is differentiated from the electrical input variable is ready, in particular with regard to the type of current (direct current, alternating current) and/or the variable (for example the amplitude, frequency and/or number of phases). As shown in fig. 1, a power electronics assembly 1 comprising switched electronic components is used, for example, in conjunction with the operation of a mechatronic system and is monitored according to the invention. The power electronics assembly 1 is a rectifier/converter comprising power semiconductors (IGBT, MOSFET, GTO …). As is known, a rectifier/converter is a power electronic component 1 which has the purpose of converting an electrical input variable/type of current fed (dc/ac, ac) into an electrical output variable/corresponding other current type or of changing characteristic variables, such as the number of phases, voltage and frequency.

In the present example, the mechatronic system comprises an electric machine 2. The electric machine 2 is, for example, a permanently excited synchronous machine comprising three phases. The mechatronic system according to fig. 1 is preferably used for driving a vehicle. The control or regulation of the electric machine 2 or the operation of the rectifier is carried out, for example, in conjunction with a Delta Sigma pulse width Modulator 3 ("Delta Sigma PWM Modulator") which supplies Pulse Width Modulation (PWM) signals S1-S6 with a modified switching frequency, so that the power semiconductors of the inverter are controlled in such a way that a phase potential ux adjustable in terms of height and frequency is ready and leads to the associated phase current ix. The construction and operation of such a Delta-Sigma pulse-width modulator 3 is known to the person skilled in the art, for example, from DE102014108667A1, WO2015193439A1 or Homann, Michael: Hochdynamiische Strom-und Spinnungsgregelung von Erterreren Synchronmaschen auf Basis von Delta-Sigma

2016, known. To this extent it is noted that the entire contents of these documents are incorporated into the present disclosure. Of course, the control and/or regulation of the electric machine 2 or the operation of the rectifier can also be carried out in conjunction with conventional pulse width modulation. Preferably, the Delta Sigma pulse width modulator 3 is an integral part of the first processing unit 3a or is implemented in connection with such a first processing unit 3 a. The first processing unit 3a is in particular an FPGA (Field Programmable gate array).

As stated, the rectifier/inverter corresponds to a power electronic assembly 1 comprising switched electronic components (here power semiconductors which are fed with the described signals S1-S6). The inverter converts/transforms/changes the direct voltage UDC/the electrical input variable into an alternating voltage u/the electrical output variable or a plurality of alternating voltages ux/a plurality of electrical output variables. The direct voltage UDC is provided, for example, by means of an energy store and the alternating voltage u/the alternating voltages ux is used to drive the electric machine 2. The dc voltage UDC can of course also be provided by means of a rectifier.

As shown in fig. 1, phase potential u1 and associated induced phase current i1 are detected, for example, by means of Delta Sigma

modulators

4a, 4b, respectively. Namely, the analog phase voltage u1 is converted into a digital bit stream u1_ b by means of the Delta Sigma modulator 4a and the analog phase current i1 is converted into a digital bit stream i1_ b by means of the Delta Sigma modulator 4 b. It is of course possible or within the scope of practical use to ascertain/convert/measure/generate the entire phase potential ux/phase current ix in this way, so that the digital bit streams ux _ b, ix _ b are accordingly ready, which, however, is not described/illustrated here for better clarity. As is known, this is achieved by a closed control loop of the respective Delta Sigma

modulator

4a, 4 b: the respective outputs u1_ b, i1_ b of the Delta Sigma

modulators

4a, 4b follow the respective analog inputs, i.e., in the present case the analog phase voltage u1 or the analog phase current i 1.

A high-resolution, highly sampled or oversampled bit stream u1_ b, i1_ b is therefore ready, which represents the phase voltage u1 or the phase current i1, respectively. Since the respective Delta Sigma

modulator

4a, 4b scans the associated analog input u1, i1 at high frequency or very high sampling rate/clock frequency, in particular at a frequency in the range of 10 to 100MHz, preferably at a frequency of 50MHz, a high-frequency, pulse-modulated bit stream u1_ b, i1_ b is generated at the output of the Delta Sigma modulator, respectively. Thus, there is convincing information of the respective valid signal u1, i1 in the respective bit stream u1_ b, i1_ b. According to the invention, the output of the Delta Sigma modulator 4a or the Delta Sigma modulator 4b (i.e. the respective bit stream u1_ b, i1_ b) is not demodulated first of all, so that the respective output is immediately/directly processed for monitoring the power electronics assembly 1/rectifier/inverter. According to the example treated here (application of Delta Sigma pulse width modulation), the rectifier or the control and/or regulation motor 2, i.e. the signals S1 to S6, are likewise operated on the basis of the bit streams u1_ b, i1_ b, which are supplied by means of Delta Sigma

modulators

4a, 4b and supplied to the Delta Sigma pulse width modulator 3. As shown in fig. 1, a bit stream u1_ b, i1_ b for monitoring the inverter is processed by a first processing unit 3a, preferably by a further processing unit 3b, which is a component of the first processing unit 3 a. In other words, the bit streams u1_ b, i1_ b represent the states or actual variables that are relevant for the operation of the mechatronic system on which the present invention is based or of the power electronic component 1 on which the present invention is based.

In this regard, according to the invention, the processing of the bit streams u1_ b, i1_ b takes place in particular in such a way that specific similarities and/or repetitions are identified in the bit streams u1_ b, i1_ b. According to the invention, therefore, the processing of the bit streams u1_ b, i1_ b, i.e. the monitoring of the power electronics module 1, consists in pattern recognition, i.e. the recognition of the changed or changing behavior of the power electronics module 1/rectifier/inverter on which it is based. According to the invention, a suitable method for pattern recognition is implemented in a comprehensive manner by means of the bit streams u1_ b, i1_ b, which are ready at the outputs of the Delta Sigma

modulators

4a, 4 b. The details of this pattern recognition and the formation of further parameters/characteristics/results R relevant for monitoring the power electronic component 1 on which it is based are also discussed in detail after the relationship based in fig. 1 is described further on.

As is also shown in fig. 1, the analog intermediate circuit/dc voltage UDC is likewise converted into a digital bit stream UDC _ b by means of a further Delta Sigma modulator 4 c. As shown in fig. 1, the processing of the bit stream UDC _ b is likewise carried out by means of a first processing unit 3a, preferably by means of a further processing unit 3b which is a constituent of the first processing unit 3 a. The bit stream UDC _ b is likewise available for forming further indicators/characteristics/results R relating to the power electronic component 1 on which the monitoring is based.

In the following process, the at least one result R of the pattern recognition is fed to a further processing unit 5. In other words, the parameters/characteristics/results R formed by means of pattern recognition and associated with the power electronic component 1 on which the monitoring is based are transmitted to/read in at the processing unit 5. The processing unit 5 is in particular a microcontroller. The transmitted result R of the pattern recognition is evaluated by means of the processing unit 5. In addition, a fault response F (fault display) and/or an alternative response E (changeover to emergency operation) is initiated in the following process by means of the diagnostic/monitoring function implemented in conjunction with the processing unit 5.

As also shown in fig. 1, the bit streams u1_ b, i1_ b are demodulated, in particular, by means of suitable low-pass filters 6a, 6 b. The signal reduced to a specific effective frequency, for example 10kHz, can then be further processed as desired, but is used in particular within the scope of the control/regulation of the relevant mechatronic system.

By processing the bit streams u1_ b, i1_ b (i.e. the outputs of the respective

Delta Sigma modulators

4a, 4 b), the invention provides pattern recognition for monitoring the power electronics module 1 (i.e. the inverter considered here) on which it is based, for example, in such a way that the behavior of the switching elements, i.e. the power semiconductors, is evaluated in view of possible changes. In other words the switching behaviour of the switches of the inverter is monitored. In this case, for example, a changed behavior (short-term observation) is identified, for example, in a defined first time period, which is shorter than a further defined time period, or, for example, in a further defined time period (long-term observation), by comparing the theoretical value with an actual value, which is (yet to be) demodulated bit stream u1_ b, i1_ b or ux _ b, ix _ b according to the invention. Such a comparison may thus relate, for example, to one or more phase voltages ux and/or phase currents ix and/or downtime. Such a comparison may also relate, for example, to the symmetry of the half bridges of the inverter with respect to one another, in particular to a comparison of the actual value (of the current and/or voltage) at one switch of the half bridge with the actual value (of the current and/or voltage) at the other switch of the half bridge or to an evaluation of the commutation, wherein the comparison is based on the (yet) unmodulated bit stream u1_ b, i1_ b or ux _ b, ix _ b, respectively, according to the invention. The identification of changed or changing behavior can be carried out according to the invention not or not only by comparing the theoretical values with the actual values, but alternatively or additionally by forming a difference D between the (temporal) ideal/reference curve and the bit stream ux _ b, ix _ b or u1_ b, i1_ b which is ready for further processing according to the invention. In this case, it is possible for the difference D to be formed from the theoretical and actual voltages or the theoretical and actual currents in a signed and/or numerical manner, and thus, if necessary, to obtain two variants of the respective at least one result R of the pattern recognition, or to open up the possibility of cancelling a partial cancellation of the difference D in the signed observation, which can be achieved by (parallel) numerical observations.

Such a pattern recognition takes place by the difference D between an ideal/reference curve (e.g. the curve of the setpoint value of the phase voltage u1_ s, which is schematically illustrated in fig. 2 by means of a dashed line) and the curve of the actual value of the phase voltage u1_ b, which is illustrated by means of a solid line (i.e. the bit stream u1_ b scanned at high resolution by means of the Delta Sigma modulator 4 a). Of course, it is also possible to form the difference D between the ideal/reference curve/curve of the setpoint value of the phase current i1_ s and the curve of the actual value of the phase current i1_ b (i.e., the bit stream i1_ b scanned with high resolution by means of the Delta Sigma modulator 4 b). As can be seen from fig. 2, there is a difference D between the curve of the setpoint value of the phase voltage u1_ s and the curve of the actual value of the phase voltage u1_ b, since the curve of the actual value of the phase voltage u1_ b has a voltage peak us which is caused by the switching on of the associated half bridge of the inverter. These voltage peaks us occur only over a very short time period of 1 to 2 microseconds and furthermore change very frequently in this time period irregularly, i.e. the phase voltage u1_ b oscillates at a high frequency in this time period, which is not shown in fig. 2. The difference D is formed by means of averaging, in particular over a defined time or over a plurality of switching processes, and when the value or value of the difference D is compared with a threshold value or a limit value, a result R of the pattern recognition is obtained if the threshold value/limit value violation is exceeded. The result R is then fed to the processing unit 5 or to a diagnostic/monitoring function and on the basis of this a fault response F (fault display) and/or a replacement response E (switching to emergency operation) is introduced. According to the invention, environmental conditions are taken into account in the pattern recognition. In particular taking into account the measured/modeled temperature values.

The result R from the pattern recognition as explained can be interpreted as a load indicator of the power electronic assembly 1 or of a construction element of the assembly 1. In other words, the result R is a characteristic variable which represents a specific load of the power electronic component 1 or of a construction element of the component 1. In particular, a service life indicator can be formed in conjunction with the processing unit 5 on the basis of the result R/the characteristic variable. The service life indicator is formed in such a way that the service life indicator decreases in time or in operating time.

In one embodiment of the invention, the service life indicator is formed from a plurality of load indicators. That is, the service life indicator is formed on the basis of other load indicators in addition to the first load indicator formed by means of pattern recognition/the at least one result R. In other words, according to the invention, a plurality of load indicators are combined to form a service life indicator. The effect of the individual load indicators on the service life indicator may be manifested differently or determined separately. In other words also the load indicators that form the basis of the service life indicators are weighted.

Each individual load indicator relates to a characteristic variable which represents a specific load of the power electronic component 1 or of a component of the component 1. Another load criterion is or relates to the power loss associated with the half-bridge of the rectifier/inverter. The power loss is formed here in particular as a function of the phase current ix and the voltage at the at least one switch or the phase voltage ux of the associated half bridge. Advantageously according to the invention, the power loss is also formed on the basis of the (high-resolution) bit streams ux _ b, ix _ b or u1_ b, i1_ b provided by means of the

Delta Sigma modulators

4a, 4 b. In this case, these variables are actually multiplied at the bit stream level in the high-frequency grid, so that the power loss during switching is determined, wherein the voltage drop of UDC _ b minus ux _ b is obtained for the upper switch shown in fig. 1. Such a differential formation is only possible due to the solution according to the invention, since the high resolution bit stream is ready. According to the invention, it is advantageous that the bit stream ix _ b relating to the phase current ix or the bit stream ux _ b relating to the phase voltage ux is not filtered before multiplying these variables, since this only provides static losses due to the voltage drop. Environmental conditions are also taken into account when determining load indicators relating to a particular load/power loss according to the invention. In particular taking into account the measured/modeled temperature values. That is, the measured temperature of the power electronics in the housing or on the circuit board is used as a load indicator as long as it is available. These temperature measurements affect the load indicator related to the power loss of the half bridge, since the hotter the environment, the more strongly weighted the shadow response due to the power loss.

According to the invention, a further load criterion relates to the ripple current load of a capacitor arranged in the intermediate circuit of the rectifier/inverter. The ripple current is preferably determined from the direct current IDC in the intermediate circuit. The direct current can either be measured by means of a further Delta Sigma modulator, which is however not shown in fig. 1 in a better outlined sense, so that a digital bit stream IDC _ b is ready, the direct current is determined by the superposition of the phase currents ix _ b, either by means of the switching pattern. The ripple current is then differentiated (at high frequency) by the digital bit stream IDC _ b from the average value of IDC over one period. The RMS value of the ripple current is then preferably determined and used as a load indicator. In particular, as explained in connection with fig. 1, in connection with the use of the Delta Sigma pulse width modulator 3, care should be taken in determining this power loss that the switching frequency is variable or that an evaluation of the ripple must be carried out in respect of the switching frequency. That is, the larger the switching frequency, the smaller the ripple. It is therefore expedient to determine the ripple as a function of the switching frequency. According to the invention, environmental conditions are also taken into account when ascertaining a load indicator relating to the power loss of the intermediate circuit capacitor. In particular taking into account the measured/modeled temperature values. That is, the measured temperature of the power electronics in the housing or on the circuit board of the assembly 1 is used as a load indicator as long as it is available.

In summary, it is clearly advantageous when the service life indicator is formed to process the (not yet demodulated) bit stream, i.e. the corresponding output of the Delta Sigma modulator, since in this way the mechatronic system/power electronics assembly 1 can be monitored continuously with great precision.

Claims

1. Method for monitoring a power electronic component (1), wherein

a) The electrical quantities are converted by means of the power electronics module (1),

b) the electrical variable according to a) is an electrical input variable (UDC), said electrical input variable is converted into at least one electrical output variable (ux, ix),

c) during the conversion according to a), a bit stream (ux _ b, ix _ b, UDC _ b) is generated by means of a Delta-Sigma modulator (4a, 4b, 4c), said bit stream representing an electrical variable according to b), or a bit stream (ux _ b, ix _ b, UDC _ b) is generated by means of a plurality of Delta-Sigma modulators (4a, 4b, 4c), said bit stream representing an electrical variable according to b),

d) monitoring of the power electronic component (1) is performed by means of the one bit stream (ux _ b, ix _ b, UDC _ b) generated according to c) or by means of a plurality of bit streams (ux _ b, ix _ b, UDC _ b) generated according to c),

e) not demodulating said one bit stream (ux _ b, ix _ b, UDC _ b) according to c) and d) or not demodulating said plurality of bit streams (ux _ b, ix _ b, UDC _ b) according to c) and d).

2. Method according to claim 1, wherein the monitoring of the power electronic component (1) is performed by pattern recognition by means of said one bit stream (ux _ b, ix _ b, UDC _ b) according to claim 1e) or by means of said plurality of bit streams (ux _ b, ix _ b, UDC _ b) according to claim 1 e).

3. Method according to claim 2, wherein said pattern recognition is performed by comparing theoretical values and actual values with each other, said actual values being said one bit stream (ux _ b, ix _ b, UDC _ b) according to claim 1e) or said plurality of bit streams (ux _ b, ix _ b, UDC _ b) according to claim 1 e).

4. A method according to claim 2 or 3, wherein a load indicator relating to the power electronic assembly (1) is formed on the basis of the result (R) of the pattern recognition, and a service life indicator relating to the power electronic assembly (1) is formed on the basis of the load indicator, the service life indicator decreasing over the operating time of the power electronic assembly (1).

5. The method of claim 4, wherein the service life indicator is formed from a plurality of load indicators.

6. Method according to claim 5, wherein a further load index is the loss power of the half bridge of the inverter, said further load index being formed by means of said one bit stream (ux _ b, ix _ b, UDC _ b) according to claim 1e) or by means of said plurality of bit streams (ux _ b, ix _ b, UDC _ b) according to claim 1 e).

7. The method according to claim 5 or 6, wherein the further load indicator is a ripple current load of a capacitor arranged in the intermediate circuit of the inverter.

8. A method according to claims 5 to 7, wherein the respective load indicators are weighted for their influence on the service life indicator.

9. Device according to claims 1 to 8, characterized in that the device is designed for carrying out a method according to one of claims 1 to 8.

10. A vehicle comprising an apparatus according to claim 9.